Automatic pressure-controlled electric switch and air-gage.



No 849,762. PATENTED APR. 9, 1907. L. H. WESTPHAL. AUTOMATIC PRESSURE CONTROLLED ELECTRIC SWITCH AND AIR GAGE.

APPLICATION FILED APR.24,1905.

INVENTOR I By I 1 flltorney s.

UNITED STATES PATENT OFFICE.

LOUIS H. WESTPHAL, OP DAVENPORT, IOWVA, ASSIGNOR TO AUTOMATIC ELECTRIC PUMP COMPANY, OF DAVENPORT, IOWA.

AUTOMATIC PRESSURE-CONTROLLED EliECTRIC SWITCH AND AIR-GAGE.

Specification of Letters Patent.

Patented April 9, 1907.

Application filed April 24, 1905. Serial No. 257,1-10.

, 1o ings, which form part of thisspec' cation.

This invention is an improvement in automatic pressure-controlled electric switches and air-gages of the type shown in the patent to Pugh, No. 765,040, of July 12, 1904.

The device is particularly adapted for use inconnection with electrical pumps for compressing air or other fluids under pressure and is designed to throw the pumps into or out of action, according as the pressure falls. below or rises above the desired point, thus maintaining a practically uniform or constant ressure at all times and economizing power By only operating the pum s when the supply of compressed fluid fa ls below the deslred minimum.

The objects of the present invention are to make the switch certain in action, to render it less liable to are and to have it close or open the circuit with a snap motion, so that when the pressure rises above the desired point the circuit will be broken instantaneously and if the pressure falls below the desired point the circuit will be closed instantaneously, thus preventing erratic and uncer- 3 5 tain actions of the electrical apparatus which controls the air-pressure.

The invention will be thoroughly understood from the following description of the apparatus illustrated in the drawings, and

0 the novel features are summarized in the claims.

- In said drawings, Figure 1 is a rear view of the gage, showing the operative arts controlling the electrical switch an showing 5 said switch closed. Fig. 2 is a similar View showing the switch open. Fig. 3 is a sectional view on line 3 3, Fig. 1, enlarged, shoW- ing the construction of the contacts. In the drawings, A designates a pneumatic 5o or.fiuid-pressure' indicator of the ordinaryv type, provided with a chamber B, commun1- cating in the usual manner with the air-reservoir (not shown) through. suitable connections so as to be subject to the pressure in the reservoir. I11 th s chamber B is a diaphragm I), of usual construction, which is pressed upon by a plunger C, attached to a stem 0, working in a'slotted cylinder C and pressed inward by .a spring C As these parts are substantially like those described in the aforesaid patent to Pugh andopcrated as described in said patent, a detailed descrip tion and illustration thereof is not required herein.

To the stem 0 of the plunger is attached an insulated block D, carrying two upstanding fingers d and d, which embrace between them an arm E, pivoted at one end on a screw F, which is attached to an insulated plate G, secured in the casing of the gage. The arm E at its free end is adapted to engage a bevel-notch 1', preferably formed in an enlargement of block *5, attached to a spring I, fixed to a bracket 1, which is ad- I justably attached to the plate G by means of a slot 1 and screw 1, as shown. The rearward swing of the arm E is limited by a bracket M, attachedto the plate G, as shown. To the pivoted end of the arm E is attached a brass spring e, which swings with the arm and has on its outer end a slotted head e, in the slot of'which is attached a platinum contact-strip 6 which is secured by placing it in the slot and then squeezing the sides of the head, so as to close the slot on the strip, thus fastening the strip to the head wthout necessarily using solder. The opposite contactan s attached to a bracket J, adjustably'see cured to plate G by means of a bolt J, passingv through a slot J in the bracket. This bracket J is preferably of brass and is provided with lugs j on its upper surface, between which-the contact 7' is placed and secured by bending down or closing over the lugs y" thereon, as shown more clearly in Fig. 3 of the drawings.

: One of the binding-posts K is connected by a wire k to the spring e, which is preferably soldered on top of the spring and above the pivot F, so that the current will not pass to or through said .pivot. The other bindingstrap j is also preferably made of platinum post Lis connected bya wire Z to the bracket 7 J, as shown. 1 The circuit therefore would be from post K through wire In to spring '0 and contacts 6 j brackets J, and wire I to post ll, provided the contacts are closed but stands in the path of the arm E and will obstruct the free swing oi the latter, so that not until spring C through finger d, exerts sufficient pressure on arm E to cause it to overcome the resistance of spring I andfo'rce arm E downward into notch 11 will the contacts be brought together; but when spring C does exert sullicient force to move arm E into notch i the movement occurs with a snap action, as is evident, and this movement causes spring-arm e to move contact e quickly against contact and hold these contacts together, closing the circuitand keep ing it closed until the pressure in the reservoir and cylinder B rises sutliciently to overcome the resistanceof spring e and move the plunger outward until finger d engages arm E and tries to move the latter outward. The outward movement of the arm E, however, is opposed by spring I through the notch i, which is engaged by arm E, and therefore pressure will accumulate against arm E through finger d until it is sul'licient to snap arm out of notch i, and upon so doing the contact a is instantly thrown away from con tact and kept away from the latter, instantaneously breaking the circuit and holding it open until the pressure in the reservoir 'lalls so much that spring e swings arm E back into engagement with notch t, as above described.

From the foregoing it will be seen that the switch is opened and closed instantly with a snap action, thus avoiding the possibility of arcing and causing the motors to operate positively, if at all, and only throwing them into action when there is a sensible decrease in the pressure.

The spring I can be regulated by adjusting bracket 1 so that the amount of pressure necessary to snap arm E into or out of notch t" can be regulated; The bracket M pre-l vents too great downward movement of the arm E, and also serves as a stop to limit the movement of block t toward the arm.

The connection and operation of the parts with the motor-pumps and compressors are explained in said patent to Pugh, and as these have nothing to do with the present invention I deem, it unnecessary to disclose the same herein. I

It will of course be understood that the invention is not limited to use in connection with air-compressors, but may be employed wherein it is desired to control an electric circuit by a fluid-pressure gage.

The beveled edge of block 4, at this time, however,

Having thus described my invention, what I claim as new, and desire to secure by Letters Pat ent,is

1. In a pressure-controlled electric switch, the combination of a fixed contact, a movable contact mounted on a spring, a pivoted arm to which said spring is attached; a notched blockadaptcd to engage the free end of said arm; an adjustable spring carrying said block; a reciprocating rod, a pneumatically-controlled plunger, adapted to move said rod in one direction, a spring for moving the rod in the opposite direction; .an insulated block attached to .said rod; and fingers'attached to said insulated block and projecting on opposite sides of said arm, substantially as and for the purpose described.

2. In combination, a swinging arm, a spring engaging said arm having a notch .for locking said arm inclosed position, a

movable contact carried by said arm; a contact fixed relatively to the arm, a rod adapted to be moved in one direction by fluid-pressure and in the opposite direction by a spring; and fingers attached to but insulated from said rod and projecting on opposite sides of said arm, for the purpose and substantially as described.

3. In a fluid-pressure electric switch, a.

pivoted arm, a movable contact connected therewith; a fixed contact opposite said movable contact; a spring having a notched block thereon engaging the free end of said arm to hold it in closed position; a fluidpressure chamber, a plunger adapted to be operated in one direction by the fluid-pressure, a spring for retracting said plunger, a

stop for limiting the spring-actuated move-- ment of the plunger and arm, and devices attached to said plunger adapted to engage said arm on opposite sides, whereby the switch is snapped open when the pressure forces the arms out of the notch and is snapped closed when the spring forces the arm into the notch.

4. In a pressure-controlled electric switch,

the combination of a fixed contact, a mow able contact mounted on a spring, a swinging arm to which said spring is attached; a notched block adaptedto engage thev free end of said arm; a spring carrying said block, an adjustable sup ort for said spring;

a reciprocating rod, insu ated fingers on said rod adapted to actuate saidarm, a pneumatically-controlled plunger adapted to to move saidrod in one direction, and a spring for moving the rod in the opposite direction.

In testimony that I claim the foregoing as my own I affix my signature in presence of two witnesses.

LOUIS H. WESTPl-IAL.

In presence-of WV. GRUENWALD, FRANK. J. Pn'ro. 

